Replace Modal with new Dialog component (#41917)

* Add Dialog component using native HTML dialog element

New component that leverages the native HTML <dialog> element for modals
and non-modal dialogs with built-in backdrop and accessibility support.

Features:
- Modal dialogs using showModal() with automatic backdrop
- Non-modal dialogs using show() for persistent UI elements
- Static backdrop option (prevents close on outside click)
- Keyboard support (Escape to close, focus trapping for modals)
- Smooth open/close animations via CSS
- Events: show, shown, hide, hidden, hidePrevented
- Data API for toggling with data-bs-toggle="dialog"

JavaScript:
- js/src/dialog.js - Main component class
- js/tests/unit/dialog.spec.js - Unit tests
- js/tests/visual/dialog.html - Visual test page

SCSS:
- scss/_dialog.scss - Component styles

Docs:
- Add dialog component documentation
- Update modal docs with dialog references

* Modal examples now Dialog examples, needs improvement

* Remove all of Modal

* real words

* Fix layout while I'm here

* Lint Markdown

* New dialog size options

Author: mdo

js/dist/modal.js

@@ -9,8 +9,8 @@ export { default as Alert } from './src/alert.js'
 export { default as Button } from './src/button.js'
 export { default as Carousel } from './src/carousel.js'
 export { default as Collapse } from './src/collapse.js'
+export { default as Dialog } from './src/dialog.js'
 export { default as Dropdown } from './src/dropdown.js'
-export { default as Modal } from './src/modal.js'
 export { default as Offcanvas } from './src/offcanvas.js'
 export { default as Popover } from './src/popover.js'
 export { default as ScrollSpy } from './src/scrollspy.js'

js/dist/modal.js.map

@@ -9,8 +9,8 @@ import Alert from './src/alert.js'
 import Button from './src/button.js'
 import Carousel from './src/carousel.js'
 import Collapse from './src/collapse.js'
+import Dialog from './src/dialog.js'
 import Dropdown from './src/dropdown.js'
-import Modal from './src/modal.js'
 import Offcanvas from './src/offcanvas.js'
 import Popover from './src/popover.js'
 import ScrollSpy from './src/scrollspy.js'
@@ -23,8 +23,8 @@ export default {
   Button,
   Carousel,
   Collapse,
+  Dialog,
   Dropdown,
-  Modal,
   Offcanvas,
   Popover,
   ScrollSpy,